To determine the response, in terms of fecal hemoglobin excretion and clinical symptoms, of normal 9½-month-old infants to being fed cow milk.
Longitudinal (before-after) trial in which each infant was fed formula for 1 month (baseline) followed by 3 months during which cow milk was fed.
Healthy infants living in Iowa City, Iowa, a town with a population of about 60,000.
Main Outcome Measures
Hemoglobin concentration in spot stools, 96-hour quantitative fecal hemoglobin excretion, stool characteristics, feeding-related behaviors, and iron nutritional status.
Fecal hemoglobin concentration during formula feeding (baseline) was higher than previously observed in younger infants. Nine of 31 infants responded to cow milk feeding with increased fecal hemoglobin concentration. Fecal hemoglobin concentration (mean±SD) of the 9 responders rose from 1395±856 µg/g of dry stool (baseline) to 2711±1732 µg/g of dry stool (P=.01). The response rate (29%) was similar to that in younger infants, but the intensity of the response was much less. Quantitative hemoglobin excretion was in general agreement with estimates based on spot stool hemoglobin concentrations. Cow milk feeding was not associated with recognizable changes in stool characteristics, nor were there clinical signs related to fecal blood loss. Iron status was similar, except that after 3 months of cow milk feeding responders showed lower (P=.047) ferritin concentrations than nonresponders.
Cow milk–induced blood loss is present in 9½-month-old infants but is of such low intensity that its clinical significance seems questionable. Nevertheless, infants without cow milk–induced blood loss were in better iron nutritional status than infants who showed blood loss.